Electrical connectors are frequently used to provide electrical connection in high voltage, low current energy systems, e.g., in systems carrying about 1000 volts up to about 50 Kv at one-half ampere or less, and the electrical transmission may be continuous or pulsed. Such connectors must operate with high reliability, often under severe environmental conditions. For example, connectors are frequently incorporated into high-voltage, electronic circuits located in hostile environments and must maintain peak performance within a broad temperature range and under diverse vaporous and gaseous conditions. In aircraft, such systems must having high reliability in a temperature range of from -55.degree. C. to +125.degree. C. and from sea level to 70,000 feet altitude, where ambient pressure is substantially lower than at sea level.
The primary problems with such high voltage applications are the discharge of voltage along a path from the connection to the environment, and the formation of corona (or voltage leakage) around the connection; both problems are aggravated under high altitude, extreme temperature conditions. Voltage discharge is a failure of the connector requiring connector replacement. Corona formation and voltage leakage commonly leads to degradation and possible breakdown of the dielectric insulation around the terminals and the conductors of the conductor wires, which commonly leads eventually to voltage discharge. To minimize corona formation and avoid voltage leakage and accompanying dielectric voltage breakdown, it is necessary that an assured airtight dielectric seal established about the terminals in their mated condition, and at the termination of the terminals with their respective conductors.
In prior art connectors for high voltage, resistance to corona formation and resultant voltage discharge is built into the connector housings by careful selection of dielectric materials, housing structure design and assembly of the terminals into the housings. In one typical high voltage connector arrangement, the pin terminal is molded within a multi-terminal receptacle housing which is adapted to be mounted to a bulkhead, and the socket terminal is disposed within a multi-terminal plug housing. The housings are secured together after mating through a conventional coupling ring rotatably mounted on the plug housing and threadedly engageable with the cylindrical housing flange defining a receptacle wall surrounding a respective pin contact section of each pin terminal in the receptacle housing. Conventionally where the terminals are inserted into passageways of a premolded housing, the conductor wires exit from the rearward housing faces and potting material is used to seal the gap between the wire insulation and the housing; the potting material minimizes the possibility of voltage discharge from the rearward face of the connector.
In U.S. Pat. No. 4,386,471, the socket terminal is terminated to a conductor wire and a respective plug housing is molded therearound of silicone rubber, and has a long axial recess extending axially thereinto from the forward face thereof to receive force-fittably thereinto the receptacle wall of the mating receptacle housing so that the silicone rubber plug wall forces practically all air from the cavity and establishes a tight grip along the inside and outside surfaces of the rigid receptacle wall; the tight air-free grip is sufficient to establish assured sealing around the mated contact interface and also adequate resistance to unintentional decoupling without other fastening means but permit intentional decoupling under sufficient axial force.
In a product of AMP Incorporated known as an LGH High Voltage Lead Assembly, Part No. 1-846290-7, a socket terminal terminated onto an insulated length of conductor undergoes an insert molding process to mold therearound a plug housing of silicone rubber such that the housing material is bonded to outer surfaces of the terminal and to an adjacent insulated portion of the conductor. The plug housing is molded to define a gradual taper to its forward end coincident with the socket terminal's forward end. The mating receptacle housing containing the pin terminal is molded of rigid dielectric material to define a cylindrical cavity into which the plug housing is received during connector mating to form a sealed mating interface surrounding the mated terminals.
In U.S. Pat. No. 4,986,764 is disclosed a matable lead assembly for a single transmission circuit, wherein a socket terminal and a pin terminal are disposed within respective cylindrical housings. A silo-shaped receptacle portion around and forwardly of the pin contact section, snugly receives thereinto a forward plug portion of reduced diameter that encases the socket contact section. Spaced apart O-rings are disposed along and tightly around the plug portion, and the O-rings are compressed by the receptacle portion and assuredly seal the annular space therebetween.
It is desired to provide improved high voltage sealing in a matable electrical connector assembly having a plurality of closely spaced mating terminals.